With conventional tubes it is often not possible to dispense liquids in the form of drops, even if the liquids are principally able to form drops. Instead the liquid is often dispensed in the form of a jet or spurt, which makes precise dosing of the liquid difficult. With some conventional tubes drop-dispensing might be possible, if a user only applies very light pressure to the tube body, which, however, can impair ease of application and user-friendliness.
As an alternative to tubes, bottles with a drop dispenser are known for dispensing liquids in the form of drops. The drop dispensers comprise a longitudinal delivery channel with an opening, through which the liquid is dispensed, with the delivery channel typically having a length that lies in the range below 1 mm and the opening typically having a diameter of up to 0.1 mm. With this rather small diameter of the opening and the rather large length of the delivery channel only a limited decrease in pressure can be achieved. With conventional drop-dispensing bottles the size of the drops thus generally depends on the user. When the user exerts a larger pressure onto the interior of the bottle, i.e. by more intense tapping on the bottom of the bottle, the liquid will trail after faster through the delivery channel, such that each drop can be fed with more liquid before it breaks away/drops from the opening of the delivery channel.
Drop-dispensing tubes are often provided with drop dispensers that consist of two elements and that are mounted onto the proximal end of the tube body from above, the proximal end of the tube body being the end from which the liquid passes into the spout. This kind of drop-dispensing tubes has interfaces between the two elements of the drop dispenser and between the drop dispenser and the inner wall of the tube spout, which interfaces must be sealing surfaces. The sealing surfaces must be dimensioned highly accurately, in particular in relation to each other. Furthermore, usually the materials of the sprout, of the elements of the drop dispenser, of the tube shoulder and of the tube body must follow a certain sequence regarding varying degrees of hardness to allow for the functioning of the drop-dispensing tube. The same material can, for example, not be used for the drop dispenser that is used for the tube shoulder. These requirements regarding the varying degrees of material hardness put a further burden on logistics and governmental approval of this kind of drop-dispensing tubes when employed for administering pharmaceutical products. Furthermore, with this kind of drop-dispensing tubes administration of liquids of high viscosity such as oils, serums, and emulsions is difficult as these liquids may more easily lead to leakage due to their better creep properties.
Patent document WO 2004/069679 A1 discloses a container with a drop dispenser. The drop dispenser has an insert element with an elongation that acts as mounting aid such that the insert can be inserted into the tube from the proximal end of the tube body and moved through the tube body and its proximal opening into the spout. The insert element comprises a lateral notch that extends into the longitudinal direction and that forms a throttling passage with the inner wall of the spout element of the drop dispenser.
While the drop dispenser disclosed in WO 2004/069679 A1 allows for improved forming of a sequence of singular drops at the spout orifice, liquid might still be dispensed in form of a jet or in form of a drizzle or spray, i.e. uncontrolled, depending on the pressure applied onto the tube body by the user.